Simulating topological robustness of Fano resonance in rotated Honeycomb photonic crystals

Abstract

The Fano resonance with a distinctive ultra-sharp, asymmetric line shape and high quality factor, is a widely occurring phenomena, that has a large variety of optical, plasmonic and microwave manifestations. In this paper, we explore the characteristic robustness of a Fano resonance mode, which is topologically protected by engineering a band inversion, induced by breaking the mirror symmetry of a two-dimensional honeycomb photonic crystal (HPC), associated with C6 point group symmetry. Dark and bright topological edge modes appear in the band gap which arise when Dirac cone is opened up. Destructive and constructive interference of the dark and bright modes leads to the asymmetric line shape of the Fano resonance. The Fano resonance is very sensitive to the material changes and structural perturbations. This property can be applied to obtain new sensor designs. Here we demonstrate that the topological Fano resonance mode preserves its asymmetric, ultra-sharp line shape in the presence of the disorder, defects and cavities.The stability of the Fano resonance mode has useful optical device applications such as in low threshold lasers, and extremely precise interferometers.